Arrangement for preventing leakage from ball-point pen cartridges

ABSTRACT

An arrangement for preventing leakage from a tubular ink cartridge including a plastic body having a frustoconical portion wedged into the end of the ink cartridge with a string extending axially through the center of the plastic body providing a plurality of small passageways, which allow air to flow into the cartridge but prevent ink from flowing outwardly, a number of the plug elements being producible simultaneously by extending a string through the cavities of a multiple-cavity mold and molding the plastic bodies around the string, with the plug elements subsequently being separated by severing the string.

United States Patent Sears et al.

151 3,698,825 [451 Oct. 17, 1972 [54] ARRANGEMENT FOR PREVENTING LEAKAGE FROM BALL-POINT PEN CARTRIDGES [72] Inventors: Hartley M. Sears, Laguna Beach; Clarence 0. Schrader, Santa Ana,

both of Calif, [73] Assignee: Frawley Enterprises, Inc., Los Angeles, Calif.

[22] Filed: May 21, 1971 [21] Appl. No.: 145,745

[52] US. Cl ..401/217, 29/450.

[51] Int. Cl. ..B43k 7/02 [58] Field of Search ..401/217 [56] References Cited UNITED STATES PATENTS 3,446,564 5/1969 I-lorie ..401/217 FOREIGN PATENTS OR APPLICATIONS 517,594 2/1953 Belgium ..40I/2 17 Great Britain ..401/2 I 7 Germany ..401/217 Primary Examiner-Lawrence Charles Attorney-Gausewitz, Carr & Rothenberg [57] ABSTRACT An arrangement for preventing leakage from a tubular ink cartridge including a plastic body having a frustoconical portion wedged into the end of the ink cartridge with a string extending axially through the center of the plastic body providing a plurality of small passageways, which allow air to flow into the cartridge but prevent ink from flowing outwardly, a number of the plug elements being producible simultaneously by extending a string through the cavities of a multiple-cavity mold and molding the plastic bodies around the string, with the plug elements subsequently being separated by severing the string.

11 Claims, 9 Drawing Figures PATENTEBHBT 1 1 1m 3.698.825

' SHEEY 1 0F 2 FIG. I

HARTLEY M, SEARS CLARENCE O. SCHRADER ARRANGEMENT FOR PREVENTING LEAKAGE FROM BALL-POINT PEN CARTRIDGES BACKGROUND OF THE INVENTION 1. Field of the Invention This invention pertains to ball-point pens.

2. Description of Prior Art In ball-point pens, obviously it is important to prevent leakage out of the end of the ink cartridge opposite from the point when the pen is in an inverted position. Under some circumstances, such leakage will occur irrespective of the inclusion of a follower ad-.

jacent the ink, such as that described in U.S. Pat. No. 2,678,634. Consequently, it has been proposed to provide some sort of stopper of porous material, sintered or foamed, in the end of the ink cartridge to allow air to flow in to avoid a vacuum as the ink is used up, at the same time blocking leakage at the cartridge end. In the design of U.S. Pat. No. 3,352,622, a fibrous element is positioned in the end of the cartridge beyond the ink for the purpose of preventing leakage.

These prior devices have presented certain practical problems which have prevented their effectively fulfilling the intended purpose. Some do not tightly grip the inner wall of the cartridge, and so may permit the ink to leak around them. Others may provide openings through them that are so large that they permit the ink to flow outwardly and do not form an effective barrier. The other extreme can occur where the passageways through the barrier device are of such small size that there is inadequate flow of air into the cartridge as the ink is used, so that a vacuum is created and the ink cannot flow outwardly at the ball point. Of importance in all instances is that the leak-preventing arrangement be not only effective, but also produced and installed economically. This is particularly significant in view of the highly competitive nature of the ball-point pen market and the low price at which ink cartridges are manufactured and sold.

SUMMARY OF THE INVENTION The present invention provides a low-cost yet fully reliable means for preventing leakage from the end of an ink cartridge for a ball-point pen. It includes a plastic body having a first portion that is adapted to enter the ink cartridge, connecting through a shoulder to a second and larger portion. The latter part of the device is cylindrical exteriorly. The first portion is frustoconical, tapering slightly to a smaller diameter at its outer end. This diameter is a little less than that of the end of the ink cartridge. Adjacent the shoulder, however, the plastic member has a diameter which is slightly larger than that of the end of the ink cartridge.

Extending through the center of the plastic body along its axis is a filamentous member in the form of a string. A nylon string, made up of several strands, is satisfactory for this use.

The plastic member is inserted into the end of the ink cartridge, bringing the shoulder into engagement with the outer edge of the ink cartridge. This tightly wedges the portion of the plastic element adjacent the shoulder into firm engagement with the interior of the cartridge. In this manner, the plastic element is secured in the end of the ink cartridge and effects a seal at its periphery so that ink cannot leak outwardly around the plastic member. The string at the axis of the plastic member provides, through its filaments, a plurality of small passageways providing between the interior and exterior of the cartridge. These passageways allow air to enter the cartridge as the ink supply is used so that a vacuum will not be created to block the flow of ink.

In the event that the ink should flow in thereverse direction to the vicinity of the end of the cartridge, it will begin to flow through the small passageways defined by the string. The ink can flow only very slowly through the small openings provided by the filaments of thestring. As the ink moves outwardly, its outer surface is exposed to air. Because of this, it will become solidified well before it reaches the outer end of the path defined by the string through the plastic member. The solidified ink acts as a solid barrier so that all outward flow is blocked. Thus, leakage is prevented.

The plug assemblies are produced by molding the plastic body around the string, which securely attaches the string and plastic body together. This may be accomplished in a multiple-cavity mold which has small passageways interconnecting the different cavities and of a diameter complementary to the string. A length of string is extended through the various cavities and the connecting openings. Then, the plastic material is introduced and, when solidified, becomes attached to the string. This produces a number of the elements attached together by the interconnecting string, produced in some respects in the way beads have been manufactured. This string is advantageous in removing the plugs from the mold and handling them during the assembly operation. The plugs are separated by severing the string adjacent the outer ends of the plastic members. This leaves a short length of string beyond the frustoconical portion of the plastic body, which in no way interferes with the function of the device.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side elevational view of a ball-point pen cartridge utilizing the present invention;

FIG. 2 is an enlarged fragmentary exploded longitudinal sectional view, partially in elevation, of the end of the ink cartridge and the plug element;

FIG. 3 is a sectional view taken along line 3-3 of FIG. 2;

FIG. 4 is an enlarged fragmentary elevational view of the string used in conjunction with the plug member;

FIG. 5 is an enlarged fragmentary longitudinal sectional view of the end portion of an ink cartridge with the plug installed and the assembly inverted;

FIG. 6 is a longitudinal sectional view of a mold arrangement for producing the plug elements;

FIG. 7 is a view similar to FIG. 6 but with the string in position prior to introducing the plastic into the mold;

FIG. 8 is a view similar to FIG. 7 but with the plastic having been introduced into the mold to become attached to the string; and

FIG. 9 is a side elevational view of the plug elements attached together following the molding operation, il-

lustrating also how the string is severed to separate them.

restricted communication DESCRIPTION OF THE PREFERRED EMBODIMENT The ink plug of this invention fits within what is normally the open outer end of a conventional tubular ball-point pen cartridge 11 which defines an ink reservoir that is cylindrical for most of its length. The solid body of the plug 10 appropriately is made of plastic, such as polypropylene. It includes a cylindrical portion 12 of relatively large diameter which connects, through a shoulder 13 to a second portion 14 of smaller diameter. The latter section of the plug is frustoconical, being larger at its base adjacent the shoulder 13 than at its outer apical end. A 45 beveled edge 15 is formed at the outer end of the larger-diameter portion 12, while a similar beveled edge 16 is at the end of the smallerdiameter portion 14. The outer end wall 17 of the plug adjacent the beveled edge 16 is inclined relative to a radial plane through the plug at an angle such as 10. Similarly, the shoulder 13 is sloped at a 10 angle relative to a radial plane. These contours for the shoulder 13 and end wall 17 facilitate removal of the plug from the mold when it is formed.

Extending axially through a central opening 18 in the plug 10 is a length of string 19, which may be made of nylon and around 0.030 inch in diameter. As seen in the enlarged view of FIG. 4, the string 19 is composed of individual strands 20, 21 and 22, each of which is made up of a multiplicity of small filaments 23. The plastic body of the plug 10 is molded in place around the string 19 so that there is a secure attachment to the string. This causes the wall of the opening 18 in the plug 10 to assume the contour of' the exterior of the string 19 so that it is complementary to the convolutions of the strands 20, 21 and 22 along the periphery of the string. A short piece of the string around one-sixteenth inch long may extend beyond the end wall 17 of the plug 10. At the opposite end, the string is flush with the end wall 24 of the plastic body.

The plug 10 is installed in the end of the cartridge 11 simply by forcing the section 14 into the cartridge, where it is securely wedged in place. The outer end of the frustoconical plug portion 14, adjacent the bevel 16, is of slightly smaller diameter than the entrance 25 to the end of the cartridge 11 to facilitate the installation of the plug 10. The bevel 16 also helps avoid interference as the plug is pushed into the cartridge. However, adjacent the shoulder 13, the portion 14 of the plug is of larger diameter than the entrance 25 to the cartridge 1 1 so that, when installed, there is a compressive force exerted on the plug, and it is firmly gripped by the tubular cartridge body. The shoulder 13 acts as a stop, positioning the plug 10 axially when it is forced into the end of the cartridge 1 1.

The plug 10 does not hermetically seal the end of the cartridge 1 1. In other words, air still may enter the cartridge through the interstices provided by the strands 20, 21 and 22, and the filaments 23, of the string 19. Accordingly, the plug 10 does not interfere with the normal operation of the cartridge, permitting air to enter as the supply of ink is used up. The ink may flow outwardly at the ball point 26 in the usual manner. This requires the string to have a diameter adequate to allow air to enter the cartridge rapidly enough to replace the volume of ink removed at the ball point 26 as the cartridge is used.

In the event that the ink 27 within the cartridge 11 flows to the end occupied by the plug 10, as shown in FIG. 5, it will beprevented from leaking outwardly around the periphery of the plug because of the tight engagement between the outer-wall of the plug and the inner surface of the cartridge. Also, the ink 27 cannot flow between the string 19 and the wall of the opening 18 in the plug 10 because of the complementary interengagement of the string and the plug. However, the ink will be able to commence flowing through the many small passageways within the string 19 at the axis of the plug 10. As the ink flows through these capillary openings, it is exposed to air and quickly dries so that it no longer is fluid. Long before reaching the outer end wall 24, the ink solidifies within the interior of the plug 10, forming a barrier that blocks any further outward movement of the ink. As a result, there is no leakage of ink from the cartridge 11.

The plugs 10 are readily manufactured by the procedure indicated in FIGS. 6, 7, 8 and 9. As illustrated, there is a multiple-cavity mold having sections 28, 29, 30 and 31, which may be extended to several more sections so as to provide simultaneous molding of a substantial number of the plugs. Cavities 32, 33 and 34 are complementary to the section 14 of the plug 10, while the cavities 35, 36 and 37 define the contour of the plug portions 12. The cavities are aligned axially and arranged so that the parting lines are at the locations where the shoulders 13 will be formed. In addition, the molds define cylindrical openings 38, 39, 40 and 41 axially interconnecting the larger cavities for forming the plug portions 12 and the smaller cavities for the portions 14 of the plug. The cylindrical openings 38, 39, 40 and 41 are complementary to the string 19-.

Initially, a length of the string 19 is placed in the mold, received in the cylindrical openings 38, 39, 40 and 41. The string also extends axially through the cavities 32, 33 and 34, as well as cavities 35, 36 and 37, as shown in FIG. 7. After this, the plastic is introduced into the mold cavities and solidified, becoming thereby attached to the string 19 (see FIG. 8).

The string is useful in removing the plugs 10 from the cavities after the molding is complete. In separating the plugs, the string 19 is sheared off at the end wall 24 of each of the plugs 10 by a suitable tool 42, as indicated in FIG. 9. This leaves the short length of string that extends beyond the end wall 17, which is not actually needed for the functioning of the plug, but which at the same time is no detriment.

A liquid repellant material, such as described in U.S. Pat. Nos. 2,662,835, 2,693,458, 2,909,545 and 2,934,450 and sold by 3M Company under the trademark Scotchgard optionally may be applied to the string 19.

The foregoing detailed description is to be clearly understood as given by way of illustration and example only, the spirit and scope of this invention being limited solely by the appended claims.

We claim:

1. A device for preventing leakage from a tubular ink cartridge or the like comprising a plastic body,

said body having an opening therethrough and a frustoconical portion for wedging into the end of a tubular ink cartridge so as to retain said plastic body therein and form a seal with respect to the surface of said ink cartridge,

and a filamentous member extending through said opening through said plastic body,

said filamentous member having convolutions along the exterior thereof complementary to the wall of said opening,

said filamentous member defining a plurality of small passageways that can transmit air into said cartridge but which will not transmit ink from said cartridge.

2. A device as recited in claim 1 in which said plastic body has a second portion of larger diameter than said frustoconical portion extending from the base end of said frustoconical portion so as to define a shoulder between said frustoconical portion and said second portion.

3. In combination with a tubular ink cartridge providing an ink reservoir having an open end, a device for preventing leakage from said open end comprising a solid body having a portion received in said reservoir at said open end, said body having a peripheral surface sealingly engaging the wall of said reservoir of said tubular ink cartridge at said open end, said body having an opening therethrough providing communication between the interior of said reservoir and the exterior thereof, and a filamentous member extending through said opening through said body,

said filamentous member having convolutions along the exterior surface thereof,

said body at said opening complementarily engaging said convolutions of said filamentous member, said filamentous member providing a plurality of small passageways through-said body for conducting air.

into said tubular ink cartridge during normal flow of ink therefrom, and exposing ink from said car tridge to air so as to cause solidification of the same in said filamentous member upon contact of said filamentous member with ink within said tubular ink cartridge for preventing leakage from said cartridge. 4. A device as recited in claim 3 in which said solid body is of plastic material.

5. A device as recited in claim 3 in which said solid body includes a portion having a frustoconical exterior wedged into said open end of said tubular ink cartridge for so sealingly engaging said tubular ink cartridge.

6. A device as recited in claim 5 in which said fila- I mentous member extends axially through said solid body.

7. A'device as recited in claim 6 in which said filamentous member is a string having a plurality of strands each of which'is made up of a plurality of filaments.

8. A device as recited in claim 7 in which said string extends outwardly beyond the apical end of said portion of said body having a frustoconical exterior.

9. A device as recited in claim 7 in which said string is of nylon material.

10. A device as recited in claim 9 in which said string is of approximately 0.030 inch diameter.

11, A device as recited in claim 5 in which said body includes a cylindrical portion of larger diameter than said frustoconical portion, said body having a shoulder between said frustoconical portion and said cylindrical portion, said shoulder engaging the edge of said open end of said tubular ink cartridge, said cylindrical portion being positioned outside of said tubular ink cartridge. 

1. A device for preventing leakage from a tubular ink cartridge or the like comprising a plastic body, said body having an opening therethrough and a frustoconical portion for wedging into the end of a tubular ink cartridge so as to retain said plastic body therein and form a seal with respect to the surface of said ink cartridge, and a filamentous member extending through said opening through said plastic body, said filamentous member having convolutions along the exterior thereof complementary to the wall of said opening, said filamentous member defining a plurality of small passageways that can transmit air into said cartridge but which will not transmit ink from said cartridge.
 2. A device as recited in claim 1 in which said plastic body has a second portion of larger diameter than said frustoconical portion extending from the base end of said frustoconical portion so as to define a shoulder between said frustoconical portion and said second portion.
 3. In combination with a tubular ink cartridge providing an ink reservoir having an open end, a device for preventing leakage from said open end comprising a solid body having a portion received in said reservoir at said open end, said body having a peripheral surface sealingly engaging the wall of said reservoir of said tubular ink cartridge at said open end, said body having an opening therethrough providing communication between the interior of said reservoir and the exterior thereof, and a filamentous member extending through said opening through said body, said filamentous member having convolutions along the exterior surface thereof, said body at said opening complementarily engaging said convolutions of said filamentous member, said filamentous member providing a plurality of small passageways through said body for conducting air into said tubular ink cartridge during normal flOw of ink therefrom, and exposing ink from said cartridge to air so as to cause solidification of the same in said filamentous member upon contact of said filamentous member with ink within said tubular ink cartridge for preventing leakage from said cartridge.
 4. A device as recited in claim 3 in which said solid body is of plastic material.
 5. A device as recited in claim 3 in which said solid body includes a portion having a frustoconical exterior wedged into said open end of said tubular ink cartridge for so sealingly engaging said tubular ink cartridge.
 6. A device as recited in claim 5 in which said filamentous member extends axially through said solid body.
 7. A device as recited in claim 6 in which said filamentous member is a string having a plurality of strands each of which is made up of a plurality of filaments.
 8. A device as recited in claim 7 in which said string extends outwardly beyond the apical end of said portion of said body having a frustoconical exterior.
 9. A device as recited in claim 7 in which said string is of nylon material.
 10. A device as recited in claim 9 in which said string is of approximately 0.030 inch diameter.
 11. A device as recited in claim 5 in which said body includes a cylindrical portion of larger diameter than said frustoconical portion, said body having a shoulder between said frustoconical portion and said cylindrical portion, said shoulder engaging the edge of said open end of said tubular ink cartridge, said cylindrical portion being positioned outside of said tubular ink cartridge. 